The present invention relates to a push wheel switch for controlling various kinds of digital mechanisms.
FIG. 1A shows a conventional push wheel switch including a housing (not shown), a set of push buttons 2 and a gear 3 disposed with numerals. The tooth face 31 of the gear 3 next to the upper/lower limit of the rotatable range being controlled is designed with an inclined surface so as to guide a gear driving arm 21 of the push button 2 to slip off from the tooth face 31 without rotating the gear 3. Two insertion pins 11 are respectively disposed next to the upper/lower limit of the set range, adjacent to the stopper block 32 for stopping the gear 3 from rotating. FIG. 1B shows that the inclined tooth face 31 has a higher H end and a lower L end, whereby when the gear driving arm 21 of the push button 2 presses the tooth face 31, the gear driving arm 21 slides toward the L end and separates from the tooth face 31.
Such a gear 3 with a specific inclined tooth face 31 is difficult to manufacture. Moreover, the stopper block 32 for restricting the rotation of travel of the gear 3 is disposed between elements 2 and 3 so that the volume of the stopper block 32 is limited. As a result, when the insertion pin 11 abuts against the stopper block 32, the stopper block 32 is often broken by the insertion pin 11.
In addition, two arch-shaped spaces are formed between the two insertion pins 11 of the gear 3. Therefore, without any definite indication, an operator often fails to identify which arch-shaped space is the correct numeral interval and thus mistakes often happen in the assembling procedure.